A user who is planning to go to a concert or a sport game is often of the mind to bring along friends or the like, and would want to secure adjacent seats for himself/herself and his/her company. Sometimes, however, whether or not there is going to be someone who accompanies the user or which friend is going to accompany the user is uncertain at the time the user reserves seats, that is, books tickets. In such cases in the past, the user would purchase tickets for himself/herself and his/her company both after it became certain who would accompany him/her, or the user would purchase tickets for himself/herself and his/her company first and then look for someone to go with.